How much blow by???

[SethSwitch]

Hello,
I know all engines have some blow by but today I noticed that a decent amount of air is coming out of my crank case vent. I don't know how to give a good idea of how much air is venting into the intake, but I would assume that about a gallon is venting every 2 minuets at idle. Should this be a sign that piston rings are going out or is this typical for the 5.3?
Thanks,
Seth


2010 Tahoe LT : 3" lift, catch can, cold air intake, Magnaflow muffler, SLP resonator delete

 

[Buzzcut]

A gallon of what venting?

 

[undy]

The standard of measurement for air movement is CFM (cubic feet per minute).

How many miles on the engine? Is it tuned? How much oil are you getting in the catch can?

You shouldn't be getting much perceivable air flow. Are you sure you piped in your catch can correctly?

 

[Buzzcut]

Catch cans aren't really needed on a naturally aspirated engine.

 

[SethSwitch]

The standard of measurement for air movement is CFM (cubic feet per minute).

How many miles on the engine? Is it tuned? How much oil are you getting in the catch can?

You shouldn't be getting much perceivable air flow. Are you sure you piped in your catch can correctly?

I would assume .33 cubic feet per minute. I don't get any oil in the catch can but it is tuned with 95,000 miles. I am positive that it is connected correctly and Justin checked it when he tuned the vehicle. It hardly burns oil so I'm hoping that this is just how these 5.3s are but wanted to get some opinions.

Seth

 

[bottomline2000]

Catch cans aren't really needed on a naturally aspirated engine.

Why would you say that?

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[Buzzcut]

Why would you say that?

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If it was required the manufacturer would have it. Just google it and you can decide for yourself. I used to race my mustang and was N/A. I never bothered as the HP level I was at and lack of supercharger wouldn't force more blow-by that would make a catch can useful or needed. I have yet see a catch-can in a normally maintained engine have any amount other than a wetness in it. Significant blow-by indicated by "larger" quantities of oil meaning it is only a band-aid to a larger issue.

YMMV

 

[undy]

If you're getting that much blow-by I'd have a leak down test performed. If your tune is off and had some detonation you could have a busted ring land or burnt valve. The stock hypereutectic pistons are very brittle and WILL NOT tolerate detonation.

The statement that NA engines don't need catch cans is totally absurd. LS engines are notorious for ingesting oil into their intake tract stock and especially when modded. The catch can minimizes combustion chamber deposits and carbon buildup on exhaust valves. I'm running one on my Z06's highly modded N/A LS7.

 

[bottomline2000]

If it was required the manufacturer would have it. Just google it and you can decide for yourself. I used to race my mustang and was N/A. I never bothered as the HP level I was at and lack of supercharger wouldn't force more blow-by that would make a catch can useful or needed. I have yet see a catch-can in a normally maintained engine have any amount other than a wetness in it. Significant blow-by indicated by "larger" quantities of oil meaning it is only a band-aid to a larger issue.

YMMV

Well I can tell you from personal experience the ls based motors need a catch can. If you ever pull the intake off one of these trucks you will see its full of oil. A lot of us are running catch cans n/a and routinely pull 50-100 cc of oil out of our catch cans between oil changes.

Our pvc systems have a design problem and I'm sure GM is aware of it but since you can get 100k out of the stock design before cats start to fail and buildup becomes a problem they simply didn't bother. Look at the "get a catch can before any mods" thread. That's all the proof u should need.

EDIT..didn't see the post from Undy until after my response..pretty much sums it up..

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[Buzzcut]

If you're getting that much blow-by I'd have a leak down test performed. If your tune is off and had some detonation you could have a busted ring land or burnt valve. The stock hypereutectic pistons are very brittle and WILL NOT tolerate detonation.

The statement that NA engines don't need catch cans is totally absurd. LS engines are notorious for ingesting oil into their intake tract stock and especially when modded. The catch can minimizes combustion chamber deposits and carbon buildup on exhaust valves. I'm running one on my Z06's highly modded N/A LS7.

If you aren't supercharged it is nothing but eye candy. But that's my opinion. You won't convince me otherwise. Been playing the hot rod game for over 30+ years and never bought the trendy catch can game over the last 10+ years. Since you called it absurd thought what data do you have the proves your point? My 170K 03 Tahoe used no oil between changes. I was my wifes DD. It would tow or haul and knock out 19-20 hwy. Changed the plugs at 100K clean as a whistle.

As I stated YMMV. What you use is great for you but I stated my opinion. You may not agree but that's life.

 

[Buzzcut]

Well I can tell you from personal experience the ls based motors need a catch can. If you ever pull the intake off one of these trucks you will see its full of oil. A lot of us are running catch cans n/a and routinely pull 50-100 cc of oil out of our catch cans between oil changes.

Our pvc systems have a design problem and I'm sure GM is aware of it but since you can get 100k out of the stock design before cats start to fail and buildup becomes a problem they simply didn't bother. Look at the "get a catch can before any mods" thread. That's all the proof u should need.

EDIT..didn't see the post from Undy until after my response..pretty much sums it up..

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My 03 hoe had original cats 170K. No oil burning. I sure it was just a fluke right?

 

[bottomline2000]

My 03 hoe had original cats 170K. No oil burning. I sure it was just a fluke right?

Unless u pulled the intake or inspected the pistons u have no way to confirm it wasn't injesting oil. My original cats made it 200k...and my intake was full of oil when I pulled it. Intake gasket was done at maybe 100k so it wasn't the 1st time it was off. I doubt your oil level remained the same over the course of an oil change. If so, consider urself lucky.

This is how much oil my catch can caught after 1 tank of gas.

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[Buzzcut]

Unless u pulled the intake or inspected the pistons u have no way to confirm it wasn't injesting oil. My original cats made it 200k...and my intake was full of oil when I pulled it. Intake gasket was done at maybe 100k so it wasn't the 1st time it was off. I doubt your oil level remained the same over the course of an oil change. If so, consider urself lucky.

This is how much oil my catch can caught after 1 tank of gas.

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Hey I get that you're defending your reason why you use it. That oil about isn't squat in the whole big picture. And just stop with the engine tear down line. That is so lame and keyboard racers been using that stuff for years. Maintenance is the key to longevity in any motor vehicle. Being swept up in the hype doesn't make your use of an item the best thing since sliced bread.

So you are saying I'm liar on my oil levels on my vehicle. Wow that's funny. Final note for you here. Luck isn't what keeps these vehicles from breakdowns, it's called proper maintenance.

 

[SethSwitch]

Ok y'all I was trying to shoot a video today to show how much blow by I was getting but got a surprise. So instead of air coming out of the crank case, it seems to be drawing a vacuum. Still not sure if this is normal. I also apologize for the poor video quality.

Seth

 

[bottomline2000]

Hey I get that you're defending your reason why you use it. That oil about isn't squat in the whole big picture. And just stop with the engine tear down line. That is so lame and keyboard racers been using that stuff for years. Maintenance is the key to longevity in any motor vehicle. Being swept up in the hype doesn't make your use of an item the best thing since sliced bread.

So you are saying I'm liar on my oil levels on my vehicle. Wow that's funny. Final note for you here. Luck isn't what keeps these vehicles from breakdowns, it's called proper maintenance.

Yeah..this is my poorly maintained keyboard racer engine..I think we're done here...

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[bottomline2000]

Ok y'all I was trying to shoot a video today to show how much blow by I was getting but got a surprise. So instead of air coming out of the crank case, it seems to be drawing a vacuum. Still not sure if this is normal. I also apologize for the poor video quality.

Seth

That may be vaccum at idle. That is the clean side of the pcv system. Mine has slight vaccum as well but not as loud. It may be the size of the hose. You can tell the difference in color of the valve springs on the pcv side as opposed to the passenger side,which is drawing in fresh air. The side you are looking at will be clean as a whistle if properly maintained..

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[Buzzcut]

Yeah..this is my poorly maintained keyboard racer engine..I think we're done here...

Actually you failed to state why this catch can was needed on an NA motor.

FWIW I can google pics showing the same thing just like you.

 

[bottomline2000]

Don't be dumb..i previously said its because of our poorly designed pvc system

Gm did change the valve cover design later to better seperate the oil in the vapor coming thru the pvc tube. Its nothing to do with maintenance.

U can't Google these pics because they are from my personal garage..but ur hard headed and seem to think I need to make this up..

Find this pic on google..

u can't because it's mine and the first time I've shared it to prove a point to a thick skulled individual..

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[Buzzcut]

Don't be dumb..i previously said its because of our poorly designed pvc system

Gm did change the valve cover design later to better seperate the oil in the vapor coming thru the pvc tube. Its nothing to do with maintenance.

U can't Google these pics because they are from my personal garage..but ur hard headed and seem to think I need to make this up..

Find this pic on google..


u can't because it's mine and the first time I've shared it to prove a point to a thick skulled individual..

Sent from my SAMSUNG-SM-G900A using Tapatalk

WOW too hardcore for you eh?